Motion-picture arc lamp



July 21, im' 1.546.601

H. W. PRETTYMAN MOTION PICTURE ARC Lun Filed June 21. 1921 2Shosetsu-Shea*1 2 Patented July 21, 1925.

UNITED `STATES HU'G'IHI W. PRETTYMAN, OF

INWOOD, WEST VIRGINIA.

MOTION-PICTURE ARC LAMP.

Application filed June 21,

To all whom it may concern.'

Be it lrnown that I, I-IUGH W. PRETTYMAN, citizen of the United States,resid-ingat Inwood, in the county of Berkeley and State of West-Virginia, have invented certain new and useful Improvements inMotion-Picture Arc Lamps, of which the following is a specifica-tion. fY

This invention relates to an improved motion picture arc lamp and has asone of itsprincipal objects to provide a construction wherein thecarbons, in addition to the usual adjustments provided therefor, mayalso be axially rotated for maintaining the proper angle between thecraters of the carbons at their confronting ends.

A further object of the invention is to provide a lamp wherein, by axialrotation of the carbons, increased efciency of the arc may be obtainedand wherein through turning of the carbons the length of service thereofmay be prolonged. Y

And the invention has as a still further object to provide a lamp welladapted for a wide range of use and wherein the carbons may be'readilymounted in position and as easily removed.

vOther and incidental objects will appear hereinafter.

' In the dra-Wings: f

Figure 1 is a side elevation of my improved lamp, the lamp house beingshown in section,

Figure 2 is a top plan view of one of "f the carbon holders employed,parts being broken away and shown in section,

Figure 3 is a. sectional view on the line 3 3 ofFigure 2, looking in thedirection of the arrows,

Figure 4 is a bottom plan view particularly showing one of the clamps ofthe carbon holders.

Figure` 5 is a fragmentary section showing a slight modification of theinvention,

Figure 6 is a detail bottom plan view of the carbon holder shown inFigure 5, and

Figure 7 is a fragmentary section vshowing a further slight modificationof the invention.

As previously intimated, the present invention seeks to provide a. meanswhereby the carbons of a motion picture arc lamp may be axially rotatedand in order to clearly bring out the function and operation of thestructure employed I have shown the invention in connection with certaincon- 192,1. Serial No. 479,358,

ventional parts of an ordinary arc lamp of the character indicated. Theimportance of maintaining a proper angle between the craters of thecarbons is well known since the realization of thegreatest efciency fromthe lamp is dependent upon this detail and while the usual feeding'- ofthe carbons serves to bring the confronting ends of, the

carbons closer together still, such feeding fails to correct thecondition brought about by wasting of the carbons att-he sides 0f thecraters thereof. The present invention, therefore, aims to overcome thedisadvantages of the usual lamp in the respects noted and, at the sametime provide a.v construction which may be embodied in practically allmotion picture arc lamps as now in common use. Referring to Figure 1, Ihave shown a lamp house 10 and upstanding within the lamp house is abracket 11 provided at its upper end with a head 12. Slidably mountedupon this head are companion rack bars 13 between which is interposed apinion 14 upon an operating shaft 15. At its outer end this shaft isprovided with a handwheel 16 which may be turned, as willY be readilyappreciated, for coincidently shifting the rack bars longitudinally and,as shall presently appear, feeding the carbons of the lamp. All of thisstructure is conventionally shown, and while I have illustrated only thefeeding adjustment still, it is to be understood that the presentinvention may be embodied in motion picture arc lamps having not only afeeding adjustment but also all of the other adjustments usuallyprovided in connection with lamps of this character. v

\ In carrying the invention into effect, I employ ca-rbon supportingrarms 17 secured at their inner ends, as shown in Figure 2, to the outerends of the raclr bars 13 by bolts 18, insulating bushingsr 19 beingarranged to surround the bolts for insulating the arms with respect tosaid bars. Integrally formed on the arms at their outer ends are rings20 at the lower edges of which are inwardly directed annular flanges 21and upstanding from the rings at the junction of the arms therewith arebosses 22. Diametrically opposite these bosses the rings are furtherprovided, asbest shown in Figure 3, with bosses 23. Snugly but rotatablyfitting within lthe rings are discs 24 seating fia-t against the fianges21 `to be rotatably supported ,thereby vand upstanding from thevperpheries of sald discs are beveled gear rings 25. The discs areprovided axially with openings 26adapted to freely receive the usualcarbons therethrough, as conventionally shown in Figure 1 at 27 and 28respectively, and mounted upon the discs at their lower sides are carbonholding clamps for rigidly connecting the carbons with the discs. Eachof these clamps includes, as best shown in Figures 3 and 4, a fixedclamp member 29 and a lcoacting pivoted clamp member 30, At their innerends, the clamp members are formed with mating lugs 31 and extendingthrough the disc 24 and through said lugs is a pin 32 pivotallysupporting the clamp member 30. Extending through the disc and throughthe outer end portion of the clamp member 29 is a second pin 33 so that,as will be seen, the pi-ns 32 and 33 will hold the clamp member 29against movement Vwhile the clamp member 30 may be swung with respectthereto. Pivoted upon the clamp member 29 at its outer end is aclampingbolt 34 which is preferably equipped with a wing nut, and formedin the outer end of the clamp member 30 to freely receive said bolt is aslot Thus, as will now be seen, after the carbons 27 and 28 have beenprojectedl through the discs 24, the

clamp members 30 of the carbon holding clamps may be swung to confrontthe clampV members 29 when, by adjusting the nuts upon the bolts 34, theclamps will be caused to securelygrip the carbons for firmly connectingthe carbons with the-discs. At the same time, the carbons may be readilyremoved when desired. In this connection it may be observed that thecarbon supporting arms are disposed at an angle with respect to eachother for sustaining the carbons 27 and 28 in proper angular relation.

Journaled through the bosses 22 of the arms 17 are operating shafts 36in which are interposed universal joints 37 each comprising acouplingblock 38Y of suitable insulating material. These blocks serve,of course, to

Y insulate the inner and outer sections ofthe shafts with respect toeachother and, as shown in Figure 1, the shafts are arranged to extendthrough the lamp house 1() and are equipped with hand wheels 39. Fixedto the inner ends of said shafts are beveled pinions40 coacting with thegear rings 25 of the discs 24 and mounted upon the bosses 23 of therings 20 to ride against said gear rings areV overhanging spring detents41. Upstanclingfrom the arms 17 are binding posts 42 to which suitableleads may be con- Y nected-for completing a circuitl through thecarbons. I

As will now be appreciated in view of the preceding description. theshafts 36 may be turned for rotating` the discs 24 and consequentlyaxially rotating the carbons 27 and 28.Y Accordingly, either of saidcarbons may, as necessity may demand, be adjustably rotated axially withrespect to the other of said carbons for maintaining the proper anglebetween the craters at the confronting ends of the carbons, the detents40 serving to lock the carbons in adjusted position. As will be seen,this axial rotation of the carbons will in no wise interfere with thefeeding of the carbons nor, infact, will said adjustment interfere withthe lateral, vertical or fore ward and rear adjustment of the lamp.Since the carbons are carried by the rack bars 13, feeding ofthe carbonsmay, of course, be accomplished by simply turning the shaft 15.

In FiguresVV 5 and of the drawings, I have illus rated aslightrinodification of the invention. In these figures, one of thelcarbon supporting arms is indicated at 17', the ring Ythereon at 2Orand Vthe'fllange of said ring at 21. An operating shaft is indicated at36 and the pinion upon said Vshaft at 40. Snugly but rotatably fittingthrough said flange is a sleeve l43 provided at Vits upper end with anoverhanging beveled gear ring 44 seating flat against the flange 21 androtatably supporting the sleeve the pinion 40 coacting with said gearring whereby the sleeve may be rotated. Threaded through the sleevebelow the ring 20is a plurality of radially disposed clamp screws 45upon the inner ends of which are swiveled arcuate clamping heads 46adapted to grip a carbon, as conventionally illustrated at 47,

therebetween. Thus, when the sleeve 43 is turned, the carbon will beaxially rotated. @therwise this modified structure is identical with thepreferred construction and provides a very convenient means of mountingthe carbons of the lamp.

I n Figure 7 of the drawings, I have illustrated a still Vfurtherrmodification of the 44 of the prior modification and formed inV theinner face of the sleeve near its lower end are concave channels 50,Threaded within the sleeve at its upper end is a tubular nut 51 andpivotally connected to the lower end of said nut are clamping members52, the free ends of which areadapted to ride in said channels. Assuggested, the nut is adapted to loosely receive a vcarbon therethrough,asfconventionally shown at 53 and, as will now be clear, the nut may beadjusted within the sleeve V48 for riding the clamping members 52downwardly withinthe sleeve into binding engagement'with the carbon.Otherwise, this modifiedk structure is identical with preferred form`-of the invention and is suggestiveof the'manner in which various minorvariations lin the structure may be made. I accordingly reserve theright to all such variations as my Vfall within the spirit of theappended claims.

Having thus described the invention, what is claimed as new is:

1. In an arc lamp, a rotatable disc, a sleeve extending from the discand provided kat its inner side with concave channels, a

tubular nutthreaded into the sleeve, and clamping members pivoted uponthe nut to ride at their free ends in said channels, the nut beingadapted to receive a carbon there through and being adjustable forshifting the clamping members in said channels to engage and clamp thecarbon.

2. In an arc lamp, an arm provided at one end with a ring having aninwardly directed annular flange at its lower edge, a disc rotatablyseated upon said flange and provided with a peripheral upstanding gearring revolubly fitting in said first mentioned ring, the disc beingapertured to receive a carbon, a clamp including coacting pivot-edmembers to engage and hold the carbon, and a pinion mounted to coactwith said gear ring for rotating the disc.

3. In an arc lamp, an arm provided at one end with a ring having aninwardly directed annular flange at its lower edge and formed at itsupper edge with a boss, a disc rotatably seated upon said flange andprovided with a peripheral upstandingY gear ring revolubly fitting insaid first mentioned ring, the disc being apertured to receive a carbon,a clamp including coacting pivoted members to engage and grip thecarbon, a shaft journaled through said boss, a pinion carried by saidshaftto coactwith said gea-r ringE for rotating the disc, and a springdetent mounted upon the former ring to coaot with the teeth of said gearring for locking the disc when rotated.

4. In arc lamp, the combination of a casing, a bracket upstandingtherein, oppositely extending rack bars slidable upon the bracket,manually operable means extending outside of the casing for shiftingsaid bars simultaneously, arms carried by said bars and provided withrings, discs journaled in said rings andV provided with gear rings, thediscs being apertured to receive carbons, means carried by the discs toengage and hold the carbons, and flexible shafts extending outside ofthe casing and provided att their inner ends with pinions to coact withsaid gear rings whereby the latter shafts may be manually turned forrotating said discs selectively.

In testimony whereof I affix my signature.

HUGH IV. PRETTYMAN. [,L. 5.]

